Recently while working on one alert, when I logged onto the server and connected SQL instance, noticed that on one of secondary replica in AlwaysOn availability group was having databases in “Synchronized/In Recovery” mode. This is not the usual status for secondary replica databases.
Replica was configured in synchronous commit mode and databases were not expected to be in recovery mode. On further check noticed that secondary replica was on higher version than primary replica.
Later discovered that this is normal when we upgrade SQL instances in AG. The secondary Replica will show ‘Synchronizing / In Recovery’ if you are in asynchronous failover mode or ‘Synchronized / In Recovery’ if you are in synchronous failover mode. It puts the databases in this state until there is a failover from the primary (prior to it’s upgrade).
Hope this information helps!
Happy Learning!!